For a skin allergic test, the allergic test conducted by a skin test device of puncture type is one of the most common ways at present. One example of such a device, as shown in FIG. 1, comprises a finger grip (A), an elongated stem (B) extending therefrom, and a plurality of puncturers (C) attached to the end of the elongated stem (B). In use, the test device, like other skin allergic test devices of prior type, is employed to press in contact with a skin portion of a patient, such as the arm skin, and then have its punctures brought into the epidermis layer (G) of the skin of a patient. A properly performed skin allergic test will leave a visible scarification which corresponds to the puncturers thereof. In the test process, a certain amount of antigen liquid loading onto puncturers by the capillary phenomenon may be transferred to the test site of the epidermis layer of the skin of the patient. Finally, the test result may be properly interpreted about 20 minutes after the specific antigen liquid has been provided.
Although various conventional skin allergic test device of the puncturer type have provided the practitioners or technicians in the art with a convenient way in performing a skin allergic test, yet none of the conventional test devices can be performed to obtain correct and reproducible test results by a person who is not a medical practitioner, since the skin allergic tests performed by any skin allergic test device of puncture type are required to meet the following test condition in order to obtain an accurate interpretation for the test result.
(1) the punctures of a skin allergic prick test device are not allowed to penetrate through the epidermis layer of the skin of a patient during the skin allergic test, as indicated in Allergic Principles And Practice, 3rd edition, P423-425, by Elliott et al.; and PA1 (2) the skin allergic test is required to be easily used by anyone with ordinary skill, therefore making the test data reproducible and assuring the reliability thereof.
However, the epidermis layer of human beings is extremely thin, it is therefore very likely for the epidermis layer of the skin to be penetrated through by the punctures of the test devices in the test process. As a result, the device as shown in FIGS. 1-3, should be operated by a medical practitioner or technician very skillful in the art in order to guarantee its reliability.
A disclosed skin allergic test device, U.S. Pat. No. 4,237,906 to Havstad et al., as shown in FIG. 3, describes an applicator or skin puncture test device having the flat end surface (E) which is provided at the end of the elongate stem (D), and a plurality of pointed projection (F) which are attached to the flat end surface (E), where the flat end surface (E) may be act as a stop to limit further penetration of the punctures in the test process .
Although the flat end surface (E) can be act as a stop to limit the depth of penetration, it is very difficult for such an applicator to be in the way that its punctures have a length between about 0.1 mm to about 0.5 mm, so as to avoid excessive penetration of the punctures. Even though such a manufacturing difficulty may be overcome, the punctures thereof will be incapable of carrying sufficient antigen liquid, by its capillarity, so as to conduct the test.
U.S. patents relating to the introduction of skin allergic test device include Brennan et al. U.S. Pat. No. 4,607,632; Maganias U.S. Pat. No. 4,802,493; Hein et al. U.S. Pat. No. 3,556,080; and Pitesky U.S. Pat. No. 5,538,134.